Autosampler with a means for detecting air bubble in specimen

Abstract

An autosampler consists of a needle to draw specimen from a specimen container into a passage therein; a block having a passage that follows the passge in the needle; a suction mechanism for drawing in the specimen by suction through the passages in the needle and the block; a discharge mechanism for discarding the specimen drawn in by the suction mechanism; and a detecting device for detecting air bubble in the specimen, the detecting device being embedded in the block in such a manner as to face the passage in the block. The detecting device detects the air bubbles in the specimen according to changes in physical or chemical properties of the specimen passing through the passage in the block. The discharge mechanism is activated by the detecting device to discharge air-mixed specimen. When even a small amount of air is drawn into the passage from the specimen container, in which only a small amount of specimen is contained, the air specimen can reliably be distinguished from normal specimen by this autosampler. Therefore the reliability of the system using the autosampler can be significantly improved.

We claim: 
     
       1. An autosampler with apparatus for detecting an air bubble in a liquid specimen, comprising: a container for containing the specimen;   a needle for drawing the specimen from the container into a passage in the needle;   a needle fixing member supporting the needle;   a block upon which the needle fixing member is detachably connected, the block having a passage therein having a cross section almost equal to the cross section of the needle passage;   a suction means for drawing in the specimen by suction through the passages in the needle and the block;   a discharge means for discarding a specimen containing an air bubble drawn in by the suction mechanism; and   a detecting means arranged in the block to face the passage in the block for detecting an air bubble in the specimen based on optical changes in the specimen flowing through the passage in the block;   whereby the discharge means is activated by the detecting means.   
     
     
       2. An autosampler with apparatus for detecting an air bubble in a liquid specimen according to claim 1, wherein the detecting means detects an amount of attenuation in intensity of light radiated from a light illuminating member of the detecting means provided near the passage in the block, wherein the light passes through the specimen in the passage in the block and is received by a light receiving member of the detecting means in the block. 
     
     
       3. An autosampler with apparatus for detecting an air bubble in a liquid specimen according to claim 2, wherein the light illuminating member is an optical fiber for introducing light from a light source into the specimen in the passage in the block, and the light receiving member is an optical fiber for transferring the light that has passed through the specimen. 
     
     
       4. An autosampler with apparatus for detecting an air bubble in a specimen according to claim 1, wherein the detecting means detects changes in intensity of light radiated from a light illuminating member provided near the passage in the block, wherein the light is received by a light receiving member in the block. 
     
     
       5. An autosampler with apparatus for detecting an air bubble in a liquid specimen according to claim 4, wherein the light illuminating member is an optical fiber for introducing light from a light source into the specimen in the passage in the block, and the light receiving member is an optical fiber for transferring the light that has been reflected by the specimen. 
     
     
       6. A autosampler with apparatus for detecting an air bubble in a liquid specimen according to claim 1, wherein the detecting means comprises an ultrasonic wave transducer provided near the passage in the block to detect change in acoustic impedance of the specimen in the passage in the block. 
     
     
       7. An autosampler with apparatus for detecting an air bubble in a liquid specimen according to claim 1, wherein the detecting means includes two electrodes inserted into the passage in the block to detect change in electric property between the electrodes. 
     
     
       8. An autosampler with apparatus for detecting an air bubble in a liquid specimen according to claim 1, wherein the detecting means produces an output only when the property change of the specimen passing through the passage in the block exceeds a specified duration of time.